Move location tracker to a separate file and refactor into class

Author: devongovett

src/index.ts

@@ -1,5 +1,6 @@
 import {Parser, ParserOptions} from 'htmlparser2';
 import {Directive, Node, NodeTag, Options, Attributes} from '../types/index.d';
+import {LocationTracker} from './location-tracker';
 
 const defaultOptions: ParserOptions = {
   lowerCaseTags: false,
@@ -16,6 +17,7 @@ const defaultDirectives: Directive[] = [
 ];
 
 const parser = (html: string, options: Options = {}): Node[] => {
+  const locationTracker = new LocationTracker(html);
   const bufArray: Node[] = [];
   const results: Node[] = [];
 
@@ -49,34 +51,6 @@ const parser = (html: string, options: Options = {}): Node[] => {
     return result;
   }
 
-  const lastLoc = {
-    line: 1,
-    column: 1
-  };
-
-  let lastIndex = 0;
-  function getLoc(index: number) {
-    if (index < lastIndex) {
-      throw new Error('Source indices must be monotonic');
-    }
-
-    while (lastIndex < index) {
-      if (html.charCodeAt(lastIndex) === /* \n */ 10) {
-        lastLoc.line++;
-        lastLoc.column = 1;
-      } else {
-        lastLoc.column++;
-      }
-
-      lastIndex++;
-    }
-
-    return {
-      line: lastLoc.line,
-      column: lastLoc.column
-    };
-  }
-
   function onprocessinginstruction(name: string, data: string) {
     const directives = defaultDirectives.concat(options.directives ?? []);
     const last: Node = bufferArrayLast();
@@ -120,11 +94,11 @@ const parser = (html: string, options: Options = {}): Node[] => {
   }
 
   function onopentag(tag: string, attrs: Attributes) {
-    const start = getLoc(parser.startIndex);
+    const start = locationTracker.getPosition(parser.startIndex);
     const buf: NodeTag = {tag};
 
     if (options.sourceLocations) {
-      buf.loc = {
+      buf.location = {
         start,
         end: start
       };
@@ -140,8 +114,8 @@ const parser = (html: string, options: Options = {}): Node[] => {
   function onclosetag() {
     const buf: Node | undefined = bufArray.pop();
 
-    if (buf && typeof buf === 'object' && buf.loc && parser.endIndex !== null) {
-      buf.loc.end = getLoc(parser.endIndex);
+    if (buf && typeof buf === 'object' && buf.location && parser.endIndex !== null) {
+      buf.location.end = locationTracker.getPosition(parser.endIndex);
     }
 
     if (buf) {

src/location-tracker.ts

@@ -0,0 +1,39 @@
+import {Position} from '../types/index.d';
+
+export class LocationTracker {
+  private readonly source: string;
+  private lastPosition: Position;
+  private lastIndex: number;
+
+  constructor(source: string) {
+    this.source = source;
+    this.lastPosition = {
+      line: 1,
+      column: 1
+    };
+
+    this.lastIndex = 0;
+  }
+
+  getPosition(index: number): Position {
+    if (index < this.lastIndex) {
+      throw new Error('Source indices must be monotonic');
+    }
+
+    while (this.lastIndex < index) {
+      if (this.source.charCodeAt(this.lastIndex) === /* \n */ 10) {
+        this.lastPosition.line++;
+        this.lastPosition.column = 1;
+      } else {
+        this.lastPosition.column++;
+      }
+
+      this.lastIndex++;
+    }
+
+    return {
+      line: this.lastPosition.line,
+      column: this.lastPosition.column
+    };
+  }
+}

test/test-core.spec.ts

@@ -248,7 +248,7 @@ test('should parse with source locations', t => {
     {
       tag: 'h1',
       content: ['Test'],
-      loc: {
+      location: {
         start: {
           line: 1,
           column: 1
@@ -266,7 +266,7 @@ test('should parse with source locations', t => {
         {
           tag: 'b',
           content: ['Foo'],
-          loc: {
+          location: {
             start: {
               line: 2,
               column: 4
@@ -278,7 +278,7 @@ test('should parse with source locations', t => {
           }
         }
       ],
-      loc: {
+      location: {
         start: {
           line: 2,
           column: 1

types/index.d.ts

@@ -21,7 +21,7 @@ export type NodeTag = {
   tag?: string | boolean;
   attrs?: Attributes;
   content?: Node[];
-  loc?: SourceLocation;
+  location?: SourceLocation;
 };
 
 export type Attributes = Record<string, string>;